The present invention relates to a micro speaker. Particularly, the present invention relates to a micro speaker in which when disassembling a protecting cover and a frame from each other, internal components are prevented from being damaged, an unnecessary squandering of resources is avoided, and an occurrence of a short circuit formation is also prevented during the installation of the speaker unit.
As shown in FIG. 1, the generally known speaker includes: a magnetic circuit part 1 consisting of a yoke part 1b, a magnet 1a mounted upon the yoke part 1b, and an upper plate 1d stacked upon the magnet 1a; an oscillating part 2 consisting of a bobbin 2c with a voice coil 2a wound thereon, an oscillating plate 2d and a damper 2b coupled to the outside of the bobbin 2c, a dust cap 2e for preventing a contaminating material from intruding into the bobbin 2c, and an edge 2g for connecting the oscillating plate 2d to a frame 4a; and a main body 4 consisting of the frame 4a for protecting the magnetic circuit part 1 and the oscillating part 2, and a gasket 4b for fixing the oscillating plate 2d to the frame 4a. 
The conventional micro speaker is constituted as shown in FIG. 2.
That is, a magnet 40 and an upper plate 50 are stacked in such a manner that a gap 30 should be formed within a frame 10 which has a magnetic circuit installing recess 20, thereby forming a magnetic circuit 80.
A voice coil 55 is wound on the lower portion of an oscillating plate 60 to be inserted into a gap 30, and the oscillating plate 60 which has a coupling face 60a is coupled to the frame 10.
A protecting cover 70 is secured to the top of the frame 10, and a terminal 85 connects the voice coil 55 to the frame 10.
In the above described micro speaker, the magnetic circuit 80 is secured into the frame, that is, into the recessed magnetic circuit securing part 20. Further, the oscillating plate 60 with the coupling face 60a is secured to the frame 10 in such a manner that the voice coil 55 can be inserted into the gap 30 which is formed between the magnetic circuit 80 and the frame 10.
The protecting cover 70 is fixed to the top of the frame 10 so as to protect the oscillating plate 60 and the magnetic circuit 80. The voice coil 55 is grounded through the terminal 85 to the circuit board 90.
Under this condition, if electrical signals are supplied through the terminal 85 to the voice coil 55, then the flow of the magnetic fluxes which occurs within the gap 30 causes the electrical signals to be converted to sounds.
However, In this speaker, when the terminal 85 which is connected to the voice coil 55 is connected to the circuit board 90, a short circuit is liable to be formed in the circuit board.
Further, if the magnetic circuit 80 or the oscillating plate 60 is defective, then the oscillating plate 60 and the frame 10 become unseparable from each other, with the result that the whole product has to be replaced, thereby bringing an otherwise unnecessary squandering resources. Further, when fixing the protecting cover, if the spreading of the bonding fluid is not perfectly uniform, then the bonding fluid may flow down to the oscillating plate 60, thereby resulting in a split resonance.
Further, the magnetic circuit 80 which is bonded onto the frame 10, the oscillating plate 60 which is inserted into the gap 30, and the protecting cover 70 are all secured by spreading a bonding fluid and by drying it in a repeated manner. Accordingly, the time for the bonding procedure is extended.
The present invention is intended to overcome the above described disadvantages of the conventional techniques.
Therefore it is an object of the present invention to provide a micro speaker in which if the magnetic circuit and oscillating plate are defective, then the protecting cover is separated from the frame to replace only the defective element, the connecting portion of the terminal cord is prevented from being contacted to the circuit board so as to prevent the formation of a short circuit, the defective spreading of the bonding fluid is minimized during the spreading of the bonding fluid, and the time required for assembling the magnetic circuit and the oscillating plate is shortened to the minimum.
In achieving the above object, the micro speaker according to the present invention includes: a frame with a yoke integrally formed therein, and with a magnetic circuit securing recess formed therein; a magnetic circuit consisting of a magnet and an upper plate, leaving a gap between the inside wall of the magnetic circuit securing recess and the magnetic circuit; a protecting cover installed on the top of the frame, and having an oscillating plate installing recess, and having a terminal cord securing piece in a projecting form; and an oscillating plate bonded to the oscillating plate securing recess, and having a voice coil on its bottom, the voice coil being connected to the terminal cord.